Big bang , physical constants , possibilities

[Crazymechanic]

Hello , so the question is basically like that , I did some thinking about evolution and so I came to this question.

Now the universe today with it's proton size and mass and particle charges , gravitational constant and all other things we know and yet don't know about , seems kinda precise and evolved , so here is the thing (according to our best understanding) the universe came into existence in an event dubbed the big bang, now before that very moment no space-time no mass and no physical laws existed, no fields as we know them no nothing, and now out of nothing the universe is born , yes way different than we know it these days , much hotter much denser and other stuff being different yet still it was " born" so to speak with a given set of rules for that moment , so these rules must have come together with the birth itself , otherwise how would the universe ,as it was,known to evolve further second by second ? I assume it had to follow some physical laws , some constants that it could fall into and so on and on until the present day.

To not make this so long and phylosophical I will try to narrow it down to a few quesions.

a) If we say taht the current state of the universe with all the current constants and laws is B , then many billions of years ago , while the universe was still in it's early stages, it had to be A which as time passed settled (evolved) down to the current state B.
Now even though back in the day the universe was in a state " A" that still is a given definite state of something with some fixed rules and possibillities , and those arose together with the universe , so that begs the question how could those rules evolve right on the spot?

In biology we are used to say that a given organism may and does evolve over a given period of time and it can happily do so because it has the environment around it and many things present for doing so , but the very fundament the very basic laws which govern the universe itself came together with the universe, so how did they assembled themselves right on the spot?

b) Did the universe in the moment or before the moment of the big bang (if we can even talk about before the big bang) had some degrees of freedom in terms of states into which it could fall into , I mean like given the same event what are the chances the physical laws could have been different back then so they would evolved to different ones at the current situation also.
I guess this last question is kinda off because we can neevr say that because we operate from a given universe with given laws and so we only have this framework.


P.S. If somebody reading this gets an angry feeling of me trying to push a set of beliefs or opinions of some religious or any other kind of thoughts , be assured this is just my own naive interest and doubt to know , so if you can please help with a healthy open discussion.
Thank you:)

 

[Drakkith]

All I can say is that the origin of the universe is unknown. It may have come from nothing or it may not have. Perhaps it has always existed.

 

[mikeph]

All you're really doing here is saying things that may or may not be true. Assigning a universe a "state" A or B is really not scientific unless you have evidence to support this. These statements are just philosophical contemplation. I think this forum is better suited to well-defined questions about things we know (or don't know) rather than wishy washy conjecture.Your understanding of the big bang theory is not correct. Nowhere is it maintained that it was the birth of the universe, just that stuff used to be much hotter and denser than it currently is. There is a lot of evidence of the latter, and none of the former, so grouping them both into a single theory just creates confusion.

 

[Crazymechanic]

Ok I agree that there is no actual physical evidence or even physical speculation as of earlier than the so called " Planck Epoch"

By state B and state A I was just reffering to the fact that the universe back then used to be (not entirely) but different than today in terms of it's density , expansion and other things , I am not saying in any way that these states don't logically follow or are just one big state which continues to evolve.As it seems so.

I do believe the question is phylosophical just because we don't have access or don't know yet the things and facts about this period of the universe.

P.S. this I believe is just as much speculation as that of many known people like Hawking , dawkins and others because atleast in the popular media and in their interviews and books they too assert definite scenarios and then build their opinion on them.I'm not saying that they say that these scenarios are a pure fact like before the big bang nothingness and others but they do talk about them.

 

[BruceW]

I'm going to avoid anything philosophical. In the very early universe, yes it was so hot and dense that all our known laws break down. This is because we don't have a quantum theory of gravity. And so, our universe was initially in that super-hot 'quantum foam' as it is sometimes called. And when it cooled out of that foam, it got the laws that we know about. So can we say anything about the foam that would explain what possible laws could have emerged, once the universe came out of the foam? I don't think so. Not without a quantum theory of gravity.

Slightly related, is chaotic inflationary theory, that Andrei Linde talks about. In this model of the universe, there are continually new parts of the universe, being created out of the foam (or being created from regions with energy close to the Planck density, I'm not sure). anyway, in this model, it is possible that the universe has no big bang as such. And a possible reason for why our laws are the way they are is because we are in a region that just happened to fall out of the foam with the laws that make life a possibility. since in each region that falls out of the foam, presumably, the laws that we know about will take on a different value. This is still quite speculative, and I don't know much of the mathematics of it, so I can't really say much about it, but it's pretty interesting.

But anyway, if we ever do get a quantum theory of gravity, or something similar, then our new laws will be different. They wold hopefully be 'better' in the sense that there are less laws, and explain more different phenomena. But still, I doubt we will ever get to the point where we have completely described the universe as one unified principle. It seems likely there will always be more problems where our theories don't quite match observation, and we must make adjustments to the theory, or introduce unexplained parameters. Even currently, our description of the universe that is below the Planck energy is still very incomplete.

 

[Crazymechanic]

Ok , I guess the question then is , out of what the physical laws are " born" ?

Do they exist before something happens ,like the universe cools down and expands, and determine what can happen and what cannot and if it can then do a certain degree , or are the laws that govern each new era of matter, created on the spot together with the process starting itself, like the one from the hot dense foam you were talking about which later settled down to a more "evolved" universe?

If the first is true then that basically means that no matter how many times one would recreate the start of the universe he would get the same or a few (out of possible many) universes , if the second one is true then we can get pretty much anything out of a primordial universe.

Now I don't intend this as some kind of speculation or self invented theory , it's rather a question about your opinion to which is the most likely answer given the current understanding that we have obtained through observation?.

 

[BruceW]

I'm not 100% sure what you mean, so I'll give an example that I think might help. OK, in the Higgs mechanism, at very high temperatures, the universe exists in a state of symmetry. In this state, electromagnetism and the weak force are both the same thing. But, when the universe cools down, the universe spontaneously drops into a specific vacuum state which breaks the symmetry. You can effectively say that the laws of the universe have changed, since now electromagnetism and the weak force are two separate things. And also, the vacuum field has taken on some specific value which is completely arbitrary. The 'true' laws of our universe don't tell us what that value is, because the true laws are symmetric, but the universe had to drop down into some specific value, so it chose some arbitrary value. There were many possible values that it could have dropped down into.

And about quantum gravity, they are not even close to such a theory (I think). But I would guess there would be a similar idea there. i.e. our current equations describe gravity and quantum as separate things, but if we had a quantum theory of gravity, then we would have equations uniting the two.

 

[Crazymechanic]

While the universe cooled and dropped down so to speak could electromagnetism and the weak force not turn into separate things ? That is what I mean.

 

[Drakkith]

While the universe cooled and dropped down so to speak could electromagnetism and the weak force not turn into separate things ? That is what I mean.

To answer this I'd say we need to recreate the conditions where the EM and Weak forces are united. Wiki says the energy range is above 100 GeV, which is well within reach of modern particle colliders. Since the particles we collide together come out of the collision acting normally, I'd say that the two forces must split at lower energies.

 

[BruceW]

While the universe cooled and dropped down so to speak could electromagnetism and the weak force not turn into separate things ? That is what I mean.

not in the current theory, I don't think so. But yeah, good point, so the guy Andrei Linde is saying that from a (very) hot state with energy density above the Planck energy, when the universe cools down from that, electromagnetism and the weak force could have turned out differently, for example, the masses of the particles could have turned out differently. But that is still mostly speculation I think. Also, it is only useful in the chaotic inflation scenario. And that is not the most accepted model of the universe, so we shouldn't really be talking about it here on physicsforums.

Anyway, in the most accepted theory (with energy density less than the Planck energy), for the electroweak theory, the Higgs field contains the information about how the electromagnetic and weak forces will work once the universe has cooled down, and the two forces become separate. For example, the Higgs field contains the information about the masses of the various particles. So really, there is only one possible way that electromagnetism and the weak force could have turned out. There is a certain amount of arbitrary choice as to which vacuum state the universe settles down in. But, these different vacuum states are essentially the same. Our universe would still seem the same in any of these states, but it is important that these states are not the same, because that is the symmetry breaking which brings about the electromagnetic and weak forces that we experience today.

 

[Crazymechanic]

thansk for the input drakkith , okay so assuming if this is the way you just said it kinda looks like the universe even though still was at a previous state (at that time) it was predetermined by some physical rules ,that may or may not have came into existence together with the universe ,to evolve into these states.

Now please don't take this as speculation , I'm just trying to follow the logic (if there is one).
My logic goes like this - if something was in a state A at some time , like the hot dense universe soon after big bang then that state was with some physical laws and constants which came together with that state or explained that state or just governed the universe at the time (choose which you like best), Now given some set of rules , the universe cannot evolve later on into something chaotic or totally unrelated to the previous state and set of rules would you agree on this one?

Edited , I didn't see you were posting also Bruce, so basically it would be fair to assume that the universe to be logic must be somehow like a tape that can be (if it would be possible) rewind back to some point and then if played again from that place do exactly what it did the time before ? Because the laws and rules wouldn't have changed so as long as the " info " is the same the playback should be also right?

And then comes the question which I meant from the very beginning , if we would to rewind to the very start , no matter how exact years ago but the very moment (assuming the universe really did came into existence from nothing) then how would we be able to explain the reason and the way some laws which seem to work on the spot came into existence just like that , even with the proposed theory of Quantum gravity and all other still yet to come stuff?
I mean no matter how precisely we could explain all the phenomenon around us both present and past , I guess it still would not answer the question , how come it assembled itself in a working manner.

 

[BruceW]

Edited , I didn't see you were posting also Bruce, so basically it would be fair to assume that the universe to be logic must be somehow like a tape that can be (if it would be possible) rewind back to some point and then if played again from that place do exactly what it did the time before ? Because the laws and rules wouldn't have changed so as long as the " info " is the same the playback should be also right?

more or less, I think so, yes, In the case of symmetry-breaking via the Higgs mechanism, the universe will generally jump down to a different vacuum state, but I don't think it affects the system. A good analogy is spontaneous magnetism in a ferromagnetic material where there is no external field. To begin with, the spins are in all different directions, then the spins will all start to align in one direction. So we have spontaneous symmetry breaking, since now there is one special direction. The particular direction that the spins align in doesn't matter, the physics is still the same. The important thing is that a direction is chosen, and that breaks the symmetry of the system.

And then comes the question which I meant from the very beginning , if we would to rewind to the very start , no matter how exact years ago but the very moment (assuming the universe really did came into existence from nothing) then how would we be able to explain the reason and the way some laws which seem to work on the spot came into existence just like that , even with the proposed theory of Quantum gravity and all other still yet to come stuff?
I mean no matter how precisely we could explain all the phenomenon around us both present and past , I guess it still would not answer the question , how come it assembled itself in a working manner.

yeah, it doesn't matter if the universe started at a specific time, or if the universe has always existed. The problem is that we have unexplained parameters and physical laws that are not unified. This problem is ongoing. Maybe one day we will have the answer to every question, maybe we won't. We just have to keep going, and finding more unified theories and trying to reduce the number of unexplained parameters.

 

[Crazymechanic]

Okay , nice answers can I ask one more question,

Now if we assume one of the possibillities that the universe has always been here , then how would we explain the current universe coming from a very hot and dense (as far as we have " seen" ) state?
I mean if it would have been always here then that would imply that after a certain point in space and time it somehow turned into a hot ultra dense singularity and then evolved to it's current state, why would it do so , because to the best of my knowledge our universe is expanding at an accelerating rate , is there any evidence or even doubt that it could somehow suddenly " turn around" and start to shrink until it becomes a singularity? Because that is how our universe started.

Also , if the universe was as you say , always here then does't that raise the question of infinities?
because as if the universe would have been always here that would imply a infinite amount of time but for that the universe would need an infinite amount of energy because we observe there is energy left in this universe just by looking at the em radiation coming from the sun , but if it would have been always here would it have enough energy left to form a shining sun at all?

 

[Drakkith]

Okay , nice answers can I ask one more question,

Now if we assume one of the possibillities that the universe has always been here , then how would we explain the current universe coming from a very hot and dense (as far as we have " seen" ) state?
I mean if it would have been always here then that would imply that after a certain point in space and time it somehow turned into a hot ultra dense singularity and then evolved to it's current state, why would it do so , because to the best of my knowledge our universe is expanding at an accelerating rate , is there any evidence or even doubt that it could somehow suddenly " turn around" and start to shrink until it becomes a singularity? Because that is how our universe started.

We don't know. These are unanswered questions in cosmology.

Also , if the universe was as you say , always here then does't that raise the question of infinities?
because as if the universe would have been always here that would imply a infinite amount of time but for that the universe would need an infinite amount of energy because we observe there is energy left in this universe just by looking at the em radiation coming from the sun , but if it would have been always here would it have enough energy left to form a shining sun at all?

Of course. We observe that there is still usable energy left in the universe, so it must be true no matter what the previous states of the universe were. Note that we have only been able to observe a small part of the universe as a whole, in both space and time. We have no idea what will happen in the far future. If the cyclic model of the universe is accurate, then eventually the universe will collapse and eventually turn back into a universe similar to the one we see today. Evidence doesn't support this, but we cannot see the future. Or perhaps the truth is far stranger than what we've even imagined.

 

[Crazymechanic]

" " Or perhaps the truth is far stranger than what we've even imagined. "

Kinda feels this might be right :D

 

[schonovic]

I think the universe is cyclic; black holes pulling in not just matter but space-time itself then reeling in each other in the end and creating a new big bang singularity and regenerating itself over and over. Weather comes in cycles why not the universe? How did it begin? I think space and time are infinite. It didn't begin by our understanding of begining.

 

[phinds]

I think the universe is cyclic; black holes pulling in not just matter but space-time itself then reeling in each other in the end and creating a new big bang singularity and regenerating itself over and over. Weather comes in cycles why not the universe? How did it begin? I think space and time are infinite. It didn't begin by our understanding of begining.

This is unsupportable personal speculation and against the forum rules. Your number of posts indicate you have been here long enough to know that.

 

[Drakkith]

I think the universe is cyclic; black holes pulling in not just matter but space-time itself then reeling in each other in the end and creating a new big bang singularity and regenerating itself over and over.

This is not correct. Black holes do not behave like this.

 

[Chronos]

It has been suggested the universe may, in the vastly distant future, be solely inhabited by super massive black holes. Due to Hawking radiation, the universe may then become devoid of matter after another few hundreds of trillions of years. That would result in a very strange initial condition - from which another big bang has been suggested as plausible.

 

[skydivephil]

We don't know. These are unanswered questions in cosmology.



Of course. We observe that there is still usable energy left in the universe, so it must be true no matter what the previous states of the universe were. Note that we have only been able to observe a small part of the universe as a whole, in both space and time. We have no idea what will happen in the far future. If the cyclic model of the universe is accurate, then eventually the universe will collapse and eventually turn back into a universe similar to the one we see today. Evidence doesn't support this, but we cannot see the future. Or perhaps the truth is far stranger than what we've even imagined.

There are cyclic models of the universe that do not involve a recollapse, Examples include Penrose CCc, Baum/Frampton model, Higgs instability models and VSl based models.

 

[Crazymechanic]

But if we give this cyclic model some credibility then I have a question , okay say the universe now goes on to expand and reach maximum entropy and all useful energy is now gone.

As the Black holes expand they " overtake" the mass of the universe.
The problematic thing here is that we don't know what happens inside a black hole because in order for them to make a new big bang they also would ahve to reverse all the entropy of the universe (read mass, and energy) that went into them.

I guess those are some troublesome big questions.

 

[julcab12]

But if we give this cyclic model some credibility then I have a question , okay say the universe now goes on to expand and reach maximum entropy and all useful energy is now gone.

As the Black holes expand they " overtake" the mass of the universe.
The problematic thing here is that we don't know what happens inside a black hole because in order for them to make a new big bang they also would ahve to reverse all the entropy of the universe (read mass, and energy) that went into them.

I guess those are some troublesome big questions.

Right now. We are not really sure what will happen. According to Wiki. Black holes will eventually evaporate via hawking radiation and after that the universe will eventually reached a extremely low energy state. Anything beyond are maths and speculations.

The best observations of the young, distant universe to date suggest that the strength of dark energy has remained steady throughout time/constant even if the distance between galaxies is stretching wider and wider and at a faster and faster rate.The density of dark energy is constant, which means that the universe expands at a fixed rate.So whatever happens in the future is a betting/hint game.

*If dark energy will remain constant = freeze;
dark energy unconstant and keeps increasing/stronger over time = rip
expansion < gravity(unknown properties) = crunch

-Hint & math-

http://arxiv.org/abs/1104.5499
https://www.technology.org/2013/08/...henomenon-black-holes-influenced-dark-energy/

"The team performed numerical calculations which indicate, that gravitational lensing is more strong at the presence of dark energy. Theoretical estimation assumed the gravitational lens created by the supermassive black hole at the center of our Milky Way galaxy.
...Calculations indicate that dark energy contributes to gravitational lensing, although the difference is not substantial. Also, from theoretical point of view, calculations yield to some degree different results for different mathematical models of black holes. Authors admit that their results have yet to be confirmed by astronomical observations using space telescopes and with sufficiently precise equipment for astronomical measurements."

 

[schonovic]

My mistake on the speculation. Thanks for pointing that out.

 

[danger9]

Sir please help me i am in trouble i had a question that can we know all the law of physics that means determinism is possible or universe is purely random? My main question is is universe deterministics or random?

 

[Drakkith]

Sir please help me i am in trouble i had a question that can we know all the law of physics that means determinism is possible or universe is purely random? My main question is is universe deterministics or random?

It is neither purely random nor is it purely deterministic. Quantum physics tells us that certain properties of atomic systems obey probabilities rather than being set, such as the position and momentum of an electron, but just because they are probabilistic does not mean they are purely random. If everything was simply pure randomness complex structures wouldn't be able to form like they do.

 

[yogi]

Theories of the beginning are at this point in our accumulation of knowledge, total speculation - its possible that the universe has a past eternal existence - at some instant the relationship between infinite space and eternal time was disrupted or as commonly phrased, the symmetry was broken and matter became the consequence - there is no reason to prefer the big bang creation of space and time over any other scenario. As Marcus once posted, to wit: we are not yet ready to ask these questions.

 

[Crazymechanic]

good point yogi , from such a perspective I think the popular science guys are doing a lot of harm many times by describing things like big bang and the suff that comes with it leaving the impression we already know every aspect about it , not to mention the times they just get something wrong themselves and then the average interested reader is left with whatever he was fed with.
Some prominent scientists among those people of the mainstream media stereotypes, too bad that making money is sometimes more important than telling the full honest truth even is she is dissatisfying

 

[ryan albery]

My intuition is that the laws of physics (and the constants) weren't born with what we currently reckon as the birth of the universe, nor do they evolve into things that can't be at least statistically predicted- or traced back in time. We don't yet understand them, but my guess is that there are laws of physics (or even philosophical concepts), which predict things, and are... mostly always true

 

[Drakkith]

My intuition is that the laws of physics (and the constants) weren't born with what we currently reckon as the birth of the universe, nor do they evolve into things that can't be at least statistically predicted- or traced back in time. We don't yet understand them, but my guess is that there are laws of physics (or even philosophical concepts), which predict things, and are... mostly always true

What?

 

[phinds]

My intuition is that ...

It's always a good idea to keep in mind that when it comes to cosmology (the very large) and quantum mechanics (the very small) human "intuition", "common sense", and so forth are generally not worth squat. I think this probably also applies to the laws of physics in general.

I'm not saying you are wrong (or right), I'm just saying that basing a conclusion like this on intuition is not a good idea.

EDIT: by the way, I have to agree w/ Drakkith that your post is a bit incoherent. Please don't do things that make me agree w/ Drakkith. I hate agreeing with him

 

[ryan albery]

I was just throwing that idea out there I suppose. Like a good buddy of mine once said, 'I'm pretty sure the physics works out.'

 

[phinds]

I was just throwing that idea out there I suppose. Like a good buddy of mine once said, 'I'm pretty sure the physics works out.'

Well, keep in mind that personal speculation is seriously frowned on here.

 

[ryan albery]

Yeah, I do understand that speculation on this forum unacceptable, but I don't think either of you guys understood what I was trying to say- in regards to the original question of this post.

 

[phinds]

Yeah, I do understand that speculation on this forum unacceptable, but I don't think either of you guys understood what I was trying to say- in regards to the original question of this post.

Since we clearly don't understand what you were saying, I'd have to agree that we didn't understand what in meant in regards to the OP.

 

[Drakkith]

Please don't do things that make me agree w/ Drakkith. I hate agreeing with him

I wonder... can we "fix" you more than once? I don't know, but I'm willing to try. :tongue: